Ukraine has claimed to have hit a Russian ship near Crimea.
In an update by the intelligence unit for the Ukrainian defence ministry, officials said the Yamal ship was struck on Saturday.
"According to Ukrainian military intelligence, the nature of the damage to the Yamal submarine is critical: a hole in the upper deck caused it to roll to the starboard side," it added.
"The occupiers are continuously pumping water out of the damaged ship, which took part in the annexation of Crimea."
Crimea was illegally annexed by Russia in 2014.
